1. Field of the Invention
The present invention relates to a method for developing the color of a crustacean such as a lobster, a crab, or the like, having a carotenoid pigment into red in a fresh state without heating, and relates to color-developed crustaceans.
2. Description of the Related Art
Crustaceans such as lobsters, crabs, etc. are popular foods because of their charming red external appearances and their deliciousness. Most of crustaceans however exhibit dark red, blue, purple or green in a fresh state, and do not turn into vivid red before they are heated. Human appetite is not stimulated before dark-color lobsters, crabs, etc. are color-developed into vivid red. Accordingly, generally, lobsters, crabs, etc. are color-developed by heating. With respect to the color development of lobsters, crabs, etc. by heating, it is considered that a pigment such as astaxanthine, or the like, which is a carotenoid pigment, is bonded to protein to thereby exhibit various color tones, and the pigment is liberated by heating so as to be color-developed into vivid red.
However, if a crustacean such as a lobster, a crab, or the like, is heated by means of boiling in water, steaming, or the like, in order to develop the color of the crustacean, protein in crustacean meat is denatured so that the quality of meat having sweetness and deliciousness peculiar thereto is quite deteriorated. Therefore, JP-A-61-242565 has proposed a method of so-called branching color development in which only the shell of a lobster is color-developed by boiling in a short time so that the quality of the meat inside the shell is kept as fresh as possible. Further, JP-A-63-129973 has disclosed a method for heating a crustacean such as a lobster, a crab, or the like, by far-infrared radiation under the presence of water vapor.
The conventional method for color development of a crustacean by boiling in a short time cannot be applied to a lobster such as "USHIEBI" (Penaeus monodon) which is generally called black tiger, or the like, and exhibits a dark color in a stripped fresh state. That is, because only the shell is color-developed, the surface of a stripped lobster cannot be color-developed into red by boiling while the quality of the meat inside the shell is kept fresh. If the surface of a stripped lobster inside the shell is color-developed by the conventional method, protein in the meat portion is necessarily denatured by heating so that the quality of the meat cannot be kept fresh. On the other hand, in the far-infrared heating method, the quality of the meat inside the shell is denatured by heating so that the quality of the meat cannot be kept fresh.
To color-develop the surface of a stripped crustacean exhibiting a dark color in a fresh state into vivid red while keeping the stripped crustacean fresh perfectly, therefore, Applicant of the present application has proposed, in Japanese Patent No. 2607204, a method for color development of a crustacean in a fresh state, comprising treating a crustacean such as a lobster, a crab, or the like, having a shell thereof left as it is or removed, with an alkaline aqueous solution to thereby develop the color of a carotenoid pigment into red.
However, if the method for color development of a crustacean disclosed in the Japanese Patent No. 2607204 is used, dark black spots appear in the surface of a stripped lobster which has been color-developed into red, when a short time is passed after the stripped lobster is color-developed into red in a fresh state. There arises a serious problem particularly in the case where dark black spots appear in a color-developed product a short time after a user has defrosted the color-developed product which had been frozen and shipped. Although the cause of the generation of such dark black spots is not yet clear, it is considered that the cause may be in the color-development chemicals remaining in the stripped body of a lobster, or the like.
Further, when a stripped lobster, or the like, which has been color-developed by the aforementioned method is subjected to a taste test, there is a case where the lobster meat is slightly bitter, resulting in some problem in taste.